Our objective is the preclinical development of an imaging technique for early detection of lymph-node metastases of prostatic carcinoma. Since prostate cancer is the second most common malignancy in American males, and since there is currently no accurate imaging modality for diagnosing such metastases, this project is of considerable clinical significance. We will exploit the inherently high uptake of polyamines, characteristic of the prostate and prostatic tumors and continue to develop positron labeled polyamines as imaging tools. The uptake of polyamines will be further stimulated by pretreatment with difluoromethylornithine(DFMO), an inhibitor of endogenous polyamine biosynthesis. Positron emission tomography(PET), will be used as the ultimate imaging device. Based on our experience thus far, we have decided to concentrate on 18F-fluorine labeled putrescine analogs. 19F-putrescine analogs will be synthesized first and screened for their ability to utilize the polyamine transport system in-vitro and in-vivo. Promising compounds will be synthesized as 18F-fluorinated (positron-emitting) substances, and used to scan animals bearing prostatic carcinoma model tumors. The best compound will be selected for animal toxicity, clearance and dosimetry studies prior to its utilization for clinical studies.